Halogenated organic nitrogen compounds and method of preparation



United States Patent HALOGENATED ORGANIC NITROGEN COM- POUNDS AND METHOD OF PREPARATION Ralph H. Bullard, Geneva, N.Y., and Alan R. Graft and A. Vern McIntosh, Jr., Cleveland, Ohio, assignors to The Lake Erie Chemical Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed June 19, 1940, Ser. No. 341,386 '1 Claim. (Cl. 260-562) This invention deals with novel organic substances incidentally found suitable as protective agents against vesciant gases.

For a long time the need has been recognized for a method of treating wearing apparel which would afford protection against the vapors of mustard gas and other vesicants and which would at the same time permit evaporation of moisture from the body. In the war of 1914-1918, military personnel assigned to the decontamination of areas which had been sprayed with mustard gas were protected by water-proof clothing completely covering the body and impervious to both air and moisture. Such garments became very uncomfortable after short periods of wear since they interfered with the normal respiration of the body through the pores of the skin. They could only be worn for a brief period of time without injury to health and this period is said to have varied from fifteen to thirty minutes depending upon the temperature and the amount of exertion required.

Over an extended period of time research has been carried out on the problem of developing a chemical substance which when fixed on ordinary wool or cotton wearing apparel, would not destroy the porosity of the cloth but which would at the same time protect the wearer against the vapors of vesicant chemical warfare agents. To be suitable for the impregnation of ordinary pervious clothing as a protection against vesicant agents, a chemical substance must meet certain rigid requirements. Among these are (a) the ability to impregnate textiles such as wool and khaki in such a manner that its protective effect will remain at a high degree of efiiciency over long periods of time; (b) the chemical equivalent of the substance in terms of the amount of vesicant agent destroyed per pound of protective substance, should be as high as possible; (0) it must be reasonably stable under ordinary temperatures, and in storage; (d) it must be reasonably stable under the action of sunlight and weather and (e) it must be non-irritating to the surface tissues of the human body.

We have ascertained by extended experiment that numerous examples of the general class of nitrogen chlorides (chloramines, chloramides and chlorimides)compounds containing a chlorine atom attached to a nitrogen atom-possess reactivity to render vesicants including mustard gas innocuous and at the same time are sufficiently stable to remain active when impregnated in clothing and subjected to normal wearing conditions. Such classes of nitrogen chlorides include the following:

(1) N-chloroacylarylamines, including monoand poly-amino compounds, and derivatives of these compounds.

(2) N-chloracylalkylamines, polyamines, and derivatives.

(3) Mono and di alkyl, aryl, and acyl derivatives of mono, di, trichlorinated ureas. Also alkyland arylacylchloramino and alkyland arylchloramino derivatives.

(4) N-chloroimides of mono, di, and polybasic acids.

(5) Quinone chlorimines, dichlorimines, and derivatives.

(6) Monoand di chloroarylsulfonamides, and derivatives.

(7) N-dichloroarylamines, and derivatives.

(8) Ring compounds containing an O O 0 II ll H N- S- or C group attached to the N-Cl or group.

(9) Monoand dichloroamides.

Not all nitrogen chlorides are suitable for impregnation or for giving a stable supply of available chlorine. The reactive chlorine atom must be sufiiciently active to render the vesicant, for example, mustard gas, innocuous, and at the same time stable enough to light, moisture, air and heat so that impregnated clothing may be worn for fairly long periods of time without losing its protective efliciency.

The problem then has been to containing the grouping in which the chlorine will have the proper degree of stability and reactivity. Such compounds exist in each of the classes mentioned above.

Certain general considerations exist in the selection of such compounds. For example, in compounds with a phenyl radical attached to the nitrogen-chlorine group, the chlorine atom has a tendency to wander into the nucleus, filling the o and p positions. This may be prevented by substituting groups in the phenyl radical which will decrease its susceptibility to chlorination. Substituting one or more of the o and p hydrogens with chlorine will increase stability towards molecular chlorination. If acyl or other groups beside the chlorine atom are attached to the nitrogen they affect the reactivity of the chlorine and its rate of transfer into the nucleus.

Among the chlorimines (containing the groups =NCl) these compounds in which the nitrogen atom is double bonded to an aromatic carbon atom seem more stable than those in which the nitrogen is double bonded to an aliphatic carbon atom, as in aldoand ketochlorimines.

Compounds containing two C=O groups attached to the N-Cl group are in general more stable than compounds containing one C=O group attached to the nitrogen. The monoand di-chlor arysulfonamides are quite stable in almost all instances.

Typical examples of stable nitrogen chlorides containing chlorine available as a protective against vesicants are N,N,2,2',4,4',-hexachlorodiphenylurea Cl CL t? a Cl C 01 and N,N, 3,3',5,5' hexachloro-N,N' diacetyl benzidine,

produce a compound 01 01 which are rather stable, apparently harmless and capable of rendering mustard gas innocuous.

Derivatives of the above compounds are also satisfactory. For example other halogens or nitro or notroso groups may be substituted in the phenyl nucleus of either compound while in the second compound formyl, propionyl, benzoyl, or other groups may replace the -acetyl groups and such may be substituted in the benzidine nuclei. "Similar variations suggest the classes of nitrogen chlorides tabulated above.

Several methods are known for making chloramines starting from acetanilide derivatives, urea derivatives, acid imides and -arylsulfonchloramides by the use of sodium or calcium hypochlorite, bleaching powder or free chlorine.

The following is given as a typical example. One part benzidine base is acetylated by refluxing with 4 parts glacial acetic acid for two to three hours. The reaction mixture is then cooled slightly and /3 part acetic anhydride is added, with stirring. The reaction mixture is refluxed for an additional hour or two, and then cooled to room temperature. The ppt. of N,N-diacetylbenzidine present is filtered ofi? as a dark gray-violet crystalline mass, melting at 3'lS"25 C. One part of this diacetylbenzidine is suspended in ten parts of acetic acid and the reaction mixture is heated to about 100 C. Excess chlorine gas is bubbled through the mixture until the color has changed to a reddish White, when samples may be withdrawn. When a sample of the insoluble compound suspended in the reaction mixture melts at 335-40, the reaction has been essentially completed. This will take six to ten hours. The reaction mixture is then cooled and the precipitate is filtered off, as a white, crystalline compound. This has been identified as 3,3,5,5'-tetrachloro-N,N-diacetylbenzidine.

The filtrate may be saved for use in following runs. "One part of the 3,3f,5,5'-tetrachloro-N,N-diacetylbenzidine is then suspended in a mixture of six parts water and one part sodium acetate. (One part alcohol, or other wetting agent, such as Turkey red oil, or benzene in suitable proportion, may be used.) The reaction mixture is heated to between 70 C. and 100 C., and excess chlorine gas is passed in. The reaction will be complete in about an hour. This will be indicated by poor absorption of chlorine. The material suspended in the reaction mixture is filtered oil as a white or cream colored solid, M.P. 200220 C. This compound has been identified as N,N,3,3',5,5-hexachloro-N,N'-diacetylbenzidine The above examples Will illustrate our invention in halogenated and particularly chlorinated derivatives of polyaryl-nitrogen compounds in which a maximum quantity of available halogen is supplied in stable form The scope of the invention is, therefore, to be limited only by the terms of the following claim.

What we claim is:

The method of preparing hexachloro-diacetyl benzidinc which consists in treating benzidine with glacial acetic acid and acetic anhydride, suspending the product in acetic acid, heating and introducing chlorine, to form a precipitate, treating the precipitate in a suspension in water and sodium acetate with gaseous chlorine at between 10 and 100 C.

References Cited in the tile of this patent Chattaway ct al. in Berichte deutsche Chem. G'eselL, vol. 34 (1901), pp. 1074 and 1077.

Schlenk in Liebigs Annalen, vol. 363 (1908), pp. 316, 334 and 335. 

